Punctuation Patterns Periods Use a period to end a sentence. Make sure the sentence is grammatically complete before you end it with a period, or you will create a sentence fragment.

Ø Correct: This is a sentence.

Ø Incorrect: Not a sentence, but a sentence fragment with a period at the end.

If you would like to know more about the grammatical definition of a sentence so you can place periods properly, see our handout “What Is a Sentence?”

Also, use periods according to convention in various abbreviations.

Ø Dr. Alvarez will check on the E. coli patient at 9:00 a.m. Semicolons A semicolon joins two independent clauses (simple sentences) together.

Ø This is an independent clause; this is an independent clause too.

A semicolon also connects two independent clauses with a transition word followed by a comma.

Ø This is an independent clause; moreover, this is an independent clause too.

For more transition words, see our handout “Transitional Devices.” For more on independent clauses, see our handout “What Is a Sentence?” Commas Use a comma and a coordinating conjunction (for, and, nor, but, or, yet, and so) to connect two independent clauses together.

Ø This is an independent clause, and this is an independent clause too.

Adding in a little bit of extra information requires commas as well.

Ø This sentence, which is a great one, contains commas around the extra bit.

Also use commas to set up dialogue or quotations in your text.

Ø Ingrid cried out, “What in the world is an independent clause already?!”

Ø “It’s just a simple sentence,” Monique replied with a shrug.

Ø “Okay,” Ingrid said after a long pause, “but then what is a sentence exactly?” Commas also connect dependent clauses to the independent clauses they rely on, but only if the dependent clause comes first.

Ø Because this clause is dependent, it needs to be connected to this independent clause.

A dependent clause might look like a sentence, but it isn’t. It depends on an independent clause to complete it. For more on dependent clauses, see our handouts “Fixing Sentence Fragments” and “What Is a Sentence?”

For much more on commas, see our handout “Using Commas.” Colons A colon comes at the end of an independent clause and tells the reader a list is coming.

Ø There are many other fantastic punctuation marks: the unconventional interrobang, the mysterious ellipsis, the eye-catching em dash, the herculean hyphen, and more!

Similarly, a colon can also tell a reader that what follows will “expand or clarify” the preceding statement (Fogarty 118).

Ø I love the colon: it always leaves a reader expecting more.

Ø There is this punctuation mark that always leaves you expecting more: the colon. Additional Information This handout lists just a few of the patterns for punctuation. For a complete list, consult a style guide, ask a writing consultant, or visit the Purdue Online Writing Lab. Here’s the QR code for that last one:

Punctuation patterns are not something you can learn in one sitting. Getting comfortable with them will take practice, so seek out resources and give yourself some time to learn the basics!

Work Cited Fogarty, Mignon. Grammar Girl Presents the Ultimate Writing Guide for Students. Illustrated by Erwin Haya. St. Martin’s Griffin, 2011.

This handout was created by the Writing Centers at YVC. Yakima Campus, Glenn-Anthon 125 | Grandview Campus, Grandview Main 101 Visit us at the Writing Center’s homepage.